WO2012/128630 relates to a scaffolding system of the type where the standards comprise supporting projections which are formed through plastic deformation of the pipe wall of the standard. The ledgers comprise couplers with the aid of which a ledger can be attached to a standard, whereby the coupling rests on a supporting projection of the standard in a ledger connecting zone of this standard. As the projections are provided through plastic deformation of the pipe wall, they do not lead to weight increase of the standard, as is the case with scaffolding systems where the standards comprise annular flanges. As a result, the supporting projections and hence the ledger can be disposed at a smaller distance from each other than the mutual distance customary with annular flanges. This offers the advantage that ledgers can be connected to standards at many different levels, which provides a greater constructive flexibility when erecting scaffolding. Another advantage of the known scaffolding coupler is that each supporting projection can support two scaffolding couplers, so that two aligned ledgers can be connected to the standard.
Generally, a scaffolding system comprises at least two standards, longitudinal ledgers and transverse ledgers. A drawback of the system described in WO2012/128630 resides in the couplers of transverse ledgers resting on the couplers of the longitudinal ledgers which in turn rest on a supporting projection, or the other way around. When, with a standard, the transverse ledger couplers rest on longitudinal ledger couplers, then, viewed in transverse direction, with the neighboring standards, longitudinal ledgers should be used too, because otherwise there is nowhere to rest the transverse ledgers that have to be connected to the standards. In some cases, this leads to placement of a larger number of longitudinal ledgers than required from a viewpoint of strength and rigidity of the entire scaffolding. The additional longitudinal ledgers are only necessary for supporting the scaffolding couplers of the transverse ledgers. The consequences are that it takes longer to erect the scaffolding and that a larger amount of longitudinal ledgers is required for erecting the scaffolding. Both consequences lead to high costs of the scaffolding, which is undesired.
The scaffolding coupler known from WO2012/128630 comprises four parts, a first casting comprising a foot and a hook integrally connected therewith, a securing element, a hinge pin with the aid of which the securing element is pivotally connected to the hook, and a wedge which is slideably received in a wedge opening in the hook. This scaffolding coupler requires several mounting operations in order to be assembled. Due to the four parts and the mounting operations, the known scaffolding coupler is relatively expensive. Another drawback of the known scaffolding coupler is that the wedge has to be struck into place at a first free end of the wedge and that the wedge can be knocked loose again from a diametrically opposed side of the ledger at a second free end of the wedge. In some cases, when erecting and dismantling scaffolding, this is quite impractical as regularly, one of the free ends of the wedge is poorly accessible for a hammer, so that knocking the wedge loose can only be done with much effort.